Dial gauge for measuring small bores



Jung 1948. E. H. ALDEBORGH ETAL 2,443,880

DIAL GAUGE FOR MEASURING SMALL BORES Filed April 5, 1946 INVENTORS in A. 4 Z7 0 z i Patented June 22, 1948 DIAL GAUGE FOR MEASURING SMALL BORES Erik Henry Aldeborgh, Poughkeepsie, Alfred Hamilton Emery, Wappifigers' Falls; and John J. Bishop and Earl M. Boat, Poiighkeepsie, N. Y., assignors toStandard Gage Company, Ina, Poughkeepsie, N. Y., a corporation of New York Application April's, 1946', Serial No. 659,760

The present invention relates to a dial bore gage and particularly to such a gage which is adapted to measuring bores of relatively small diameter.

In the past, dial bore gages have been extensively used but have been used only inthe larger sizes since the construction thereof was such as to make it substantially impossible to constructagage which would measure bores of a diameter less than /1: of an'inch. One form of construction of a dial bore gage which has been extensively' used forthe measurement of large bores is that shown in United States Patent No. 2,095,405, issued to Erik B. Aldeborgh on October 12, 1937; The gage of that patent illustrates a mode of centering which comprises utilizing radial pins,

one on'either side of the measuring plunger, which pins are spring pressed outwardly'by a common spring so that the pressure forces the gage into positionxalong a diameter ofthe bore measured and thereby causes the measuring plunger to be correctly located and to give an indication of the linear dimension of the diameter.

By our present invention we supply a dial indicator gage capable of measuring small bores'and providedwith centralizing pins similar to those ofJthe-patent above mentioned. The centralizing pins areso' located and'the spring means for pressing-them outwardly isso constructed as to make the measurement of small'bores possible andtthus I provideaii instrument which heretofore has been greatly desired but has not been commercially feasible;

It is an object of our invention to provide a diai'bore'gage of the'dial indicator type capable of: measuring the internal diameter of bores of relatively small size.

It is another object of our invention to providev such-a gage in which a means is provided to as-' sure that the measurementwillbe taken along the diameter of the bore.

It is still another object of our invention to providesuch a gage adapted to extremely accu-' rate measurement and provided with means for extending the range of the instrument;

' Itis a further object of our invention to pro-'- vid'e such a bore gage in which the dial" indicator itself: is a standard type of instrument.

Other objects and features of the invention" will appear'whenv the following descriptionis considered in connection with the annexed drawing: in which Figure 1 is a plan view of the dial bore gage of our "invention .Figure2 isa fragmentary crosssectionalview r 3 Claims. (oi. 33-178) of the measuring element of the gage showingthe details of construction thereof and particularly thedetails of the measuring plunger;

Figure 3 is a transverse cross sectional view of the gage of Figure 1 taken on the plane of the line 3-3 of Figure 1, showing particularly the construction of the centralizing plungers and the mode by which these plungers cooperate with a common spring means for pressing them out wardly against the bore walls; and

Figure 4 is a fragmentary cross sectional view of the gage of our invention taken on the plane of the line 4-4 of Figure 3 showing in greater detail the mode of cooperation between the cen- L tralizing plungers and their common spring mounteda dial indicator H of a common midget type. The housing It) is provided with a handle l2' and with a measuring unit Iii-which measuring unit terminates in a somewhat enlarged end which carries the measuring plunger Is as well: as the centralizing-plungers l6.

As wi1l be seen in Figure 2, the measuring unit generally designated 83 consists of a sleeve I! which extends into a bore in the housing l0 and is fastened therein as may be seen in Figure 1. Fixed'to the sleeve i1 is another sleeve l8 and inturn fixed to the sleeve I8 is a cylindrical block '2 ll. Asiis clearly seen in Figure 2, a plunger 2! extends through the sleeves I1 and I8 and is guided in a bore 22 in the block 29. This plunger extendsintohousing In and bears against the usual plunger of the dial indicator ll so that any movement of the plunger 21 is effective to cause a om-responding indication on the dial indicator. i

A sleeve member zae tenes between the sleeve [8- and: block 20', being seated in a peripheral groove 24 in the block flit-and being held in. position by virtue of" the threading of the block 29 on the reduced extension 2501 sleeve iii. The

block ZiI'is provided with a radialbore 26 located plunger Ziiispressed outwardly and into contact button 33 and the stud being locked into any adjusted position by means of the lock or jam nut 34. By adjustment of the stud 32 in its threaded bore the gage may be adjusted to measure over a limited range and by replacing the stud 32 with one of greater length this range' of measurement may be extended. In the particular gage which we have constructed in accordance with our invention a number of studs 32 are provided, one being adapted to measure dimensions in the range of from to -6", at second from 3%" to /2", a third from to and the fourth in the range between a" and /3 In order to retain the measuring plunger in its bore 26 and to limit the movement thereof the plunger is provided with a flat surface and a shouldered screw 35 is inserted into a tapped hole of the'block 29 and bears against the flat 35. By this arrangement it is possible to readily assemble the plunger into the block and retain the plunger in the block while limiting the movement thereof.

As has been indicated it is necessary in a gage of this type, i. e., in a gage for measuring bores, that means be provided for assuring that the measurement taken is actually that of the diameter of the cylinder or bore being measured and not some chord of the cylinder. In order to accomplish this we provide a pair of centralizing plungers l6 each of which is located in a bore 31 in the block 20. These bores do not extend radially of the cylindrical block 20 but are at an acute angle to the diameter thereof and the bores are of considerably .greater than radial length. Each of the plungers or pins I6 is provided at its innermost end with a slot 38 in which is mounted a roller M1, the roller being rotatable upon a shaft ll extending through the pin on the opposite sides of the slot 38.

As was the case for the measuring plunger PS the plungers [ii are limited in their range of movement by means of the shoulder screw 42 threaded into the bores 43 in the block 20 as is particularly seen in Figure 4. Rollers M3 bear against and cooperate with 45 angled faces Ml of rods 45 which extend generally longitudinally of the measuring head l3 and make contact at their right hand ends (as seen in Figure 4) with the terminating surface d6 of a collar 41. Collar 4! slides upon the extension 25 of the sleeve l8 and is spring pressed to the left as seen in Figures 2 and 4 by means of a coil spring 50, one end of which bears against the flange 48 of the collar 41 and the other end of which bears against a shou1- der 5! on the interior of the sleeve 23.

Due to the construction above described the two plungers it are urged outwardly to the same extent by means of the spring 50 and upon insertion of the gage measuring head into a bore the plungers it cause the .gage head to lie centrally of the bore so that the measurement taken by the measuring plunger l5 and the cooperating button 32 is along, a diameter of the inscribed circle of the bore at the point of measurement. If, upon its first insertion, the head of the gage is not properly positioned in the bore, one plunger will make contact with the bore wall, and the spring pressure exerted by the spring 58 is pressed solely against that one plunger and consequently the gage is moved until the spring pressure is exerted equally on the two plungers l6. Since these two plungers are equally spaced from the plunger l5 it follows that when the spring pressure is thus equally exerted the measuring head of the gauge is properly located and the plunger l5 lies along a diameter of the bore.

- It will be seen that due to the use of our construction t he centralizing plungers need not be radial and the spring pressure may be exerted upon them without extending the radial dimens-ion of the measuring head and therefore a bore gage is provided which is capable of measuring holes of lesser diameter than have previously been measured with a bore gage of this type.

While we have described a preferred embodiment of our invention it will be understood by those skilled in the art that our invention is capable of various modifications and we do not desire therefore to :be restricted to the particular details shown and described but only within the scope of the appended claims.

What is claimed is:

1. In a dial bore gage of the type having a radial measuring plunger and cooperating centralizing plungers, in combination, a measuring head having a measuring plunger slid-ably mounted in a radial bore therein, means for transmitting radial movement of said measuring plunger at right angles thereto and along the axis of'the measuring head to a dial indicator, a stud extending in alignment with said measuring plunger and radially of the measuring head, a pair of centralizing plungers slidably mounted in nonradial bores in said measuring head and one on either side of said measuring plunger, said centralizing and measuring plungers being co-planar, means for transmitting movement of said centralizing plungers longitudinally of said measuring head, a collar located co-axially in said measuring head and abutting said last mentioned -means, and spring means for moving said collar into engagement with said last mentioned means to thereby spring press said centralizing plungers simultaneously outwardly against the walls of the bore.

2. In a dial bore gage of the type having a radial measuring plunger and cooperating centralizing plungers, in combination, a measuring head generally cylindrical in shape, a measuring plunger mounted in a radial bore in said measuring head, means for transmitting radial movement of said measuring plunger axially of said measuring head and to a dial indicator, a measuring stud located in a radial bore of said measuring head and on the same diameter as said measuring plunger, a pair of centralizing plungers located in non-radial bores in said measuring head and in the same transverse plane as said measuring plunger, said centralizing plungers being of greater length than the radius of said measuring head, movement transmitting pins located in longitudinal bores in said measuring head and extending into the bores in which said centralizing plungers operate, mean-s for causing longitudinal movement of said motion transmitting ins upon inward and outward movement of the associated centralizing plungers, a collar slidable axially of said measuring head and bearing against the ends of said movement transmitting pins remote from said centralizing plungers, and a resilient member operating upon said collar for moving said movement transmitting pins to cause outward movement of said centralizing plungers, said resilient member being compressed upon inward movement of either one of said centralizing plungers, whereby the measuring head is caused to take a position in .the bore such that the measuring plunger and its cooperating stud lie on a diameter of the inscribed circle of the bore.

3. In a dial bore gage of the type having a radial measuring plunger and cooperating centralizing plungers, in combination, a measuring head generally cylindrical in shape, a. measuring plunger mounted in a radial bore in said measuring head, means for transmitting radial movement of said measuring plunger axially of said measuring head and 130 a dial indicator, a measuring stud located in a radial bore of said measuring head and on the same diameter as cated in non-radial bores in said measuring head and in the same transverse plane as said measuring plunger, said centralizing plungers being of greater length than the radius of said measuring head, movement transmitting pins located in longitudinal bores in said measuring head and extending into the bores in which said centralizing plungers operate, a roller mounted in the inner end of each of said centralizing plungers, an angular face on each of said movement transmitting pins, said faces cooperating with said rollers to move said pins longitudinally upon inward movement of said centralizing plun-gers, a c lar o at d. sc -a i l y of sa d m asu i g head,

said measuring plunger, a pair of centralizing plungers lo- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,030,244 Cox Feb. 11, 1936 2,095,405 Aldeborgh et a1. Oct. 12, 1937 2,152,880 Dowdy et a1. Apr. 4, 1939 2,253,803 Newberry Aug. 26, 1941 2,268,579 Eisele Jan. 6,1942

' 2,325,996 Eisele Jan. 6, 1942 2,385,122 Worthen Sept. 18, 1945 2,424,497 Nilsson July 22, 1947 FOREIGN PATENTS Number Country Date 415,971 Germany July 7, 1925 456,576 Great Britain Nov. 11, 1936 

